Struct Store 

pub struct Store { /* private fields */ }

The embedded keyspace.

Store is Clone (since v1.1.0). A clone is a cheap Arc bump: every clone reaches the same underlying kevy_store::Store + AOF + reaper + pub/sub bus. The reaper thread is joined and the AOF is flushed exactly once, when the last clone is dropped.

use kevy_embedded::{Config, Store};

let s = Store::open(Config::default().with_ttl_reaper_manual())?;
let s2 = s.clone();
std::thread::spawn(move || {
    s2.set(b"from-thread", b"v").unwrap();
}).join().unwrap();
assert_eq!(s.get(b"from-thread")?, Some(b"v".to_vec()));

Every method takes &self. The internal Arc<Mutex<Inner>> is what makes shared access safe under contention.

Implementations

impl Store

pub fn set(&self, key: &[u8], value: &[u8]) -> Result<bool>

SET key value (no TTL, no NX/XX). Returns true always under the embedded API (Redis semantics: SET overwrites; NX/XX vetoes would return false but we don’t expose those here — use Store::with for the full surface).

Examples found in repository

examples/embedded.rs (line 9)

fn main() -> std::io::Result<()> {
    let s = Store::open(Config::default())?;
    s.set(b"greeting", b"hello, kevy")?;
    let v = s.get(b"greeting")?;
    println!("greeting = {}", String::from_utf8_lossy(v.as_deref().unwrap_or(b"<missing>")));
    println!("dbsize = {}", s.dbsize());
    Ok(())
}

examples/embedded-cache.rs (line 19)

fn main() -> std::io::Result<()> {
    let s = Store::open(
        Config::default()
            .with_max_memory(200 * 1024)
            .with_eviction(EvictionPolicy::AllKeysLru),
    )?;

    for i in 0..10_000 {
        let key = format!("user:{i:05}");
        let val = format!("user-payload-{i}");
        s.set(key.as_bytes(), val.as_bytes())?;
    }

    println!("dbsize after insert flood: {}", s.dbsize());
    println!("used_memory: {} bytes (limit 200 KiB)", s.used_memory());
    println!("evictions_total: {}", s.evictions_total());

    // Touch a recent key — it should still be live.
    let recent = format!("user:0{}", 9999);
    println!(
        "user:09999 → {:?}",
        s.get(recent.as_bytes())?.as_deref().map(String::from_utf8_lossy)
    );

    Ok(())
}

pub fn set_with_ttl( &self, key: &[u8], value: &[u8], ttl: Duration, ) -> Result<bool>

SET key value PX ms — overwrites + sets TTL.

pub fn get(&self, key: &[u8]) -> Result<Option<Vec<u8>>>

GET key — Some(bytes) on hit, None on miss or expired.

Examples found in repository

examples/embedded.rs (line 10)

fn main() -> std::io::Result<()> {
    let s = Store::open(Config::default())?;
    s.set(b"greeting", b"hello, kevy")?;
    let v = s.get(b"greeting")?;
    println!("greeting = {}", String::from_utf8_lossy(v.as_deref().unwrap_or(b"<missing>")));
    println!("dbsize = {}", s.dbsize());
    Ok(())
}

examples/embedded-cache.rs (line 30)

fn main() -> std::io::Result<()> {
    let s = Store::open(
        Config::default()
            .with_max_memory(200 * 1024)
            .with_eviction(EvictionPolicy::AllKeysLru),
    )?;

    for i in 0..10_000 {
        let key = format!("user:{i:05}");
        let val = format!("user-payload-{i}");
        s.set(key.as_bytes(), val.as_bytes())?;
    }

    println!("dbsize after insert flood: {}", s.dbsize());
    println!("used_memory: {} bytes (limit 200 KiB)", s.used_memory());
    println!("evictions_total: {}", s.evictions_total());

    // Touch a recent key — it should still be live.
    let recent = format!("user:0{}", 9999);
    println!(
        "user:09999 → {:?}",
        s.get(recent.as_bytes())?.as_deref().map(String::from_utf8_lossy)
    );

    Ok(())
}

pub fn del(&self, keys: &[&[u8]]) -> Result<usize>

DEL key1 [key2 ...]. Returns the count of keys actually removed.

pub fn exists(&self, keys: &[&[u8]]) -> Result<usize>

EXISTS key1 [key2 ...]. Count of existing keys (duplicates counted multiple times, matching Redis).

pub fn incr(&self, key: &[u8]) -> Result<i64>

INCR key. Returns the post-increment value.

pub fn incr_by(&self, key: &[u8], delta: i64) -> Result<i64>

INCRBY key delta. Negative delta does DECR-style work.

pub fn expire(&self, key: &[u8], ttl: Duration) -> Result<bool>

EXPIRE key seconds. Returns true if a key was touched.

pub fn persist(&self, key: &[u8]) -> Result<bool>

PERSIST key. Returns true if a TTL was actually cleared.

pub fn ttl_ms(&self, key: &[u8]) -> i64

Remaining TTL in ms (or Redis-style -1/-2 for no-TTL/no-key).

pub fn type_of(&self, key: &[u8]) -> &'static str

TYPE key — "string", "hash", "list", "set", "zset", or "none".

pub fn dbsize(&self) -> usize

DBSIZE — total live keys.

Examples found in repository

examples/embedded.rs (line 12)

fn main() -> std::io::Result<()> {
    let s = Store::open(Config::default())?;
    s.set(b"greeting", b"hello, kevy")?;
    let v = s.get(b"greeting")?;
    println!("greeting = {}", String::from_utf8_lossy(v.as_deref().unwrap_or(b"<missing>")));
    println!("dbsize = {}", s.dbsize());
    Ok(())
}

examples/embedded-cache.rs (line 22)

fn main() -> std::io::Result<()> {
    let s = Store::open(
        Config::default()
            .with_max_memory(200 * 1024)
            .with_eviction(EvictionPolicy::AllKeysLru),
    )?;

    for i in 0..10_000 {
        let key = format!("user:{i:05}");
        let val = format!("user-payload-{i}");
        s.set(key.as_bytes(), val.as_bytes())?;
    }

    println!("dbsize after insert flood: {}", s.dbsize());
    println!("used_memory: {} bytes (limit 200 KiB)", s.used_memory());
    println!("evictions_total: {}", s.evictions_total());

    // Touch a recent key — it should still be live.
    let recent = format!("user:0{}", 9999);
    println!(
        "user:09999 → {:?}",
        s.get(recent.as_bytes())?.as_deref().map(String::from_utf8_lossy)
    );

    Ok(())
}

pub fn flush(&self) -> Result<()>

FLUSHALL — empty the keyspace (logged so a replay reaches the same empty state).

pub fn key_bytes(&self, key: &[u8]) -> Option<u64>

MEMORY USAGE for one key — Some(bytes) or None if absent.

pub fn used_memory(&self) -> u64

Live used_memory estimate (matches INFO memory’s field).

Examples found in repository

examples/embedded-cache.rs (line 23)

fn main() -> std::io::Result<()> {
    let s = Store::open(
        Config::default()
            .with_max_memory(200 * 1024)
            .with_eviction(EvictionPolicy::AllKeysLru),
    )?;

    for i in 0..10_000 {
        let key = format!("user:{i:05}");
        let val = format!("user-payload-{i}");
        s.set(key.as_bytes(), val.as_bytes())?;
    }

    println!("dbsize after insert flood: {}", s.dbsize());
    println!("used_memory: {} bytes (limit 200 KiB)", s.used_memory());
    println!("evictions_total: {}", s.evictions_total());

    // Touch a recent key — it should still be live.
    let recent = format!("user:0{}", 9999);
    println!(
        "user:09999 → {:?}",
        s.get(recent.as_bytes())?.as_deref().map(String::from_utf8_lossy)
    );

    Ok(())
}

pub fn evictions_total(&self) -> u64

INFO-style counter: total keys evicted by maxmemory so far.

Examples found in repository

examples/embedded-cache.rs (line 24)

fn main() -> std::io::Result<()> {
    let s = Store::open(
        Config::default()
            .with_max_memory(200 * 1024)
            .with_eviction(EvictionPolicy::AllKeysLru),
    )?;

    for i in 0..10_000 {
        let key = format!("user:{i:05}");
        let val = format!("user-payload-{i}");
        s.set(key.as_bytes(), val.as_bytes())?;
    }

    println!("dbsize after insert flood: {}", s.dbsize());
    println!("used_memory: {} bytes (limit 200 KiB)", s.used_memory());
    println!("evictions_total: {}", s.evictions_total());

    // Touch a recent key — it should still be live.
    let recent = format!("user:0{}", 9999);
    println!(
        "user:09999 → {:?}",
        s.get(recent.as_bytes())?.as_deref().map(String::from_utf8_lossy)
    );

    Ok(())
}

pub fn expired_keys_total(&self) -> u64

INFO-style counter: total keys expired (lazy + active reaper).

pub fn hset(&self, key: &[u8], pairs: &[(&[u8], &[u8])]) -> Result<usize>

HSET key field value [field value ...]. Returns count newly added.

pub fn hget(&self, key: &[u8], field: &[u8]) -> Result<Option<Vec<u8>>>

HGET key field. None if absent.

pub fn hdel(&self, key: &[u8], fields: &[&[u8]]) -> Result<usize>

HDEL key field [field ...]. Returns count actually removed.

pub fn lpush(&self, key: &[u8], values: &[&[u8]]) -> Result<usize>

LPUSH key value [value ...]. Returns the new list length.

pub fn rpush(&self, key: &[u8], values: &[&[u8]]) -> Result<usize>

RPUSH key value [value ...]. Returns the new list length.

pub fn lpop(&self, key: &[u8], count: usize) -> Result<Vec<Vec<u8>>>

LPOP key count. Returns popped values from the head.

pub fn rpop(&self, key: &[u8], count: usize) -> Result<Vec<Vec<u8>>>

RPOP key count. Symmetric to LPOP from the tail.

pub fn llen(&self, key: &[u8]) -> Result<usize>

LLEN key. Length of the list at key; 0 if absent.

pub fn sadd(&self, key: &[u8], members: &[&[u8]]) -> Result<usize>

SADD key member [member ...]. Returns count newly added.

pub fn srem(&self, key: &[u8], members: &[&[u8]]) -> Result<usize>

SREM key member [member ...]. Returns count actually removed.

pub fn smembers(&self, key: &[u8]) -> Result<Vec<Vec<u8>>>

SMEMBERS key. Order implementation-defined; empty if absent.

pub fn scard(&self, key: &[u8]) -> Result<usize>

SCARD key. Member count; 0 if absent.

pub fn zadd(&self, key: &[u8], pairs: &[(f64, &[u8])]) -> Result<usize>

ZADD key score member [score member ...]. Returns count newly added.

pub fn zrem(&self, key: &[u8], members: &[&[u8]]) -> Result<usize>

ZREM key member [member ...]. Returns count actually removed.

pub fn zscore(&self, key: &[u8], member: &[u8]) -> Result<Option<f64>>

ZSCORE key member. Some(score) if present.

pub fn zcard(&self, key: &[u8]) -> Result<usize>

ZCARD key. Member count; 0 if absent.

pub fn publish(&self, channel: &[u8], payload: &[u8]) -> usize

PUBLISH channel payload. Delivers payload to every subscriber on channel (direct + pattern matches) inside this process. Returns the count of receivers the message reached.

pub fn subscribe(&self, channels: &[&[u8]]) -> Subscription

Open a Subscription subscribed to channels. Drop the handle to unsubscribe from everything atomically. Pass &[] to start with no subscriptions and add some later via Subscription::subscribe / Subscription::psubscribe.

pub fn psubscribe(&self, patterns: &[&[u8]]) -> Subscription

Convenience: open a Subscription starting on pattern subscriptions.

impl Store

pub fn open(config: Config) -> Result<Self>

Open an embedded keyspace per config.

• Pure in-memory when config.data_dir is None.
• With persistence: loads <data_dir>/<snapshot_filename> first, then replays <data_dir>/<aof_filename>. Both are best-effort — missing files are fine, a truncated AOF tail is silently dropped.
• Spawns a background TTL reaper thread when config.ttl_reaper == Background (the default).

Examples found in repository

examples/embedded.rs (line 8)

fn main() -> std::io::Result<()> {
    let s = Store::open(Config::default())?;
    s.set(b"greeting", b"hello, kevy")?;
    let v = s.get(b"greeting")?;
    println!("greeting = {}", String::from_utf8_lossy(v.as_deref().unwrap_or(b"<missing>")));
    println!("dbsize = {}", s.dbsize());
    Ok(())
}

examples/embedded-cache.rs (lines 10-14)

fn main() -> std::io::Result<()> {
    let s = Store::open(
        Config::default()
            .with_max_memory(200 * 1024)
            .with_eviction(EvictionPolicy::AllKeysLru),
    )?;

    for i in 0..10_000 {
        let key = format!("user:{i:05}");
        let val = format!("user-payload-{i}");
        s.set(key.as_bytes(), val.as_bytes())?;
    }

    println!("dbsize after insert flood: {}", s.dbsize());
    println!("used_memory: {} bytes (limit 200 KiB)", s.used_memory());
    println!("evictions_total: {}", s.evictions_total());

    // Touch a recent key — it should still be live.
    let recent = format!("user:0{}", 9999);
    println!(
        "user:09999 → {:?}",
        s.get(recent.as_bytes())?.as_deref().map(String::from_utf8_lossy)
    );

    Ok(())
}

pub fn downgrade(&self) -> WeakStore

Get a weak handle that does not keep the keyspace alive. upgrade() returns None once the last strong Store is dropped.

pub fn config(&self) -> &Config

The active config (a clone — modifying it has no effect on the running store). Useful for introspection / INFO-style telemetry.

pub fn with<F, R>(&self, f: F) -> R

where F: FnOnce(&mut Store) -> R,

Run f against the underlying kevy_store::Store under the embedded mutex. Use for direct access to methods this crate hasn’t wrapped (snapshot iteration, ZRANGE, raw collect_keys, …). The closure can mutate, but does not auto-log to the AOF — call Self::log yourself if the mutation must survive a crash.

pub fn log(&self, parts: &[&[u8]]) -> Result<()>

Append a raw RESP-frame argument list to the AOF. Pairs with Self::with when the closure performed a write you want to make crash-safe. No-op when persistence is disabled.

pub fn tick(&self) -> ExpireStats

Run one TTL-reaper tick. Required call cadence in Manual mode (call ~10× per second to match Redis’s hz=10); no-op cost is one mutex lock + map-emptiness check when nothing has TTL.

pub fn rewrite_aof(&self) -> Result<Option<RewriteStats>>

BGREWRITEAOF: rebuild the AOF from current state. Synchronous — blocks until the rewrite + atomic rename completes. Returns Ok(None) when persistence is disabled.

pub fn save_snapshot(&self) -> Result<bool>

Snapshot the store to <data_dir>/<snapshot_filename>, atomically. Ok(false) when persistence is disabled (caller can decide to surface that or no-op).

Trait Implementations

impl Clone for Store

fn clone(&self) -> Store

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.